Methane VS Hydrogen — The Battle of the Gases
Global energy consumption is on the rise since the industrial revolution and is only set to increase with time. For the longest time, energy demands have been met using fuels such as Petroleum, Hydrocarbon Gas Liquids, Coal, Natural Gas and Nuclear Energy. Apart from being non-renewable, these sources of energy have negative impacts on the environment. Sustainable energy sources are now being adopted to meet the current and future energy demands. Read our article on the energy of the future to learn more!
Methane is widely used as fuel in the form of natural gas but its uncontrolled emission is an environmental hazard. Hydrogen is an alternative fuel that is gaining popularity due to its clean burning process to generate energy. This article will provide a comparison between the two most popular gaseous fuels.
Methane
Methane, a colourless and odourless gas, is the primary component of natural gas. It is lighter than air and insoluble in water. It readily burns in air making it a suitable candidate for energy generation. Methane’s relative abundance on Earth’s surface and clean burning process make it a very attractive fuel.
1. Sources of methane emissions
Methane can be naturally produced in two major ways. First, methane can be produced through the decomposition of organic matter decomposed at shallow depths in low-oxygen environments, such as swamps and bogs. As plants die and sink to the bottom of these watery environments, bacteria start to break them down and release methane in the process. Consequently, wetlands are the single largest natural contributor to methane emissions. Methane can also leak from mud volcanoes, rice fields, and strangely, termites.
Second, methane can be found in underground fossil fuel deposits that have been subjected to high pressure and temperatures over millions and millions of years. As these fuels are harvested, mined, and released, so is methane. Methane is difficult to transport and easily leaks during the extraction of oil, coal, and natural gas.
Methane gas hydrates, a form of methane mixed with ice, can be found trapped in layers of sediment on the ocean floor and beneath permafrost and frozen lakes in the Arctic. Despite being a potential energy source, these gas hydrates can be sources of uncontrolled emissions of concentrated methane.
2. How is it used as a fuel?
Methane combustion provides for a significant amount of the world’s primary energy demand. Methane, a major constituent of natural gas, is used for power generation, domestic use, transportation, and as a feedstock for the production of ammonia-based fertilizers.
To power road transport vehicles, methane is used in compressed state, i.e., in the form of compressed natural gas (CNG) or compressed biogas (CBG), and for long distance travel, natural gas is usually shipped as liquified natural gas (LNG), which is then re-gasified in coastal terminals to be injected into the natural gas grid.
3. Environmental impact
- Explosions
Methane is considerably inflammable and given that air consists of 20 % oxygen, methane-air mixtures are prone to explosions. There have been cases of explosions, especially in coal mines, where the reaction between the methane gas in the mine and the oxygen in the air have caused mines to collapse.
Explosions have also been reported in landfills where high concentrations of methane from organic waste react spontaneously with the air around the landfill and cause a fire outbreak.
- Greenhouse effect
Methane gas when isolated is of no harm to the environment or life. However, increased concentrations of the gas coupled with the presence of carbon dioxide and water vapor cause substantial absorption and trapping of heat in the atmosphere that is harmful to the environment. The result is termed as the greenhouse gas effect associated with climate change and global warming.
- Climate change
Following carbon dioxide, methane is responsible for about 23% of climate change witnessed in the twentieth century as per NASA. Methane, when released into the atmosphere before it is burned, is harmful to the environment. In comparison to other greenhouse gases, methane’s lifespan in the atmosphere is short, but it is more efficient at trapping heat than the other gases. Its ability to trap a lot of heat is a significant contributor to climate change.
Hydrogen
Hydrogen is colorless, odorless, tasteless, non-toxic, and non-poisonous. It is the most fundamental and abundant element on the planet. It has the ability to store and release usable energy, but it is rarely found in nature and must be synthesised from chemical compounds that contain it.
1. Sources
- Thermal processes
Thermal processes for hydrogen production typically involve steam reforming wherein steam reacts with a hydrocarbon fuel to produce hydrogen. Hydrocarbon fuels can be reformed to produce hydrogen are — natural gas, diesel, renewable liquid fuels, gasified coal and gasified biomass. Presently, about 95% of all hydrogen is produced from steam reforming of natural gas.
- Electrolytic processes
Water can be split into oxygen and hydrogen through a process called electrolysis. Electrolytic processes take place in an electrolyser, which creates hydrogen from water molecules.
- Solar-driven processes
Solar-driven processes use light as the driver for hydrogen production. Some of these solar-driven processes are termed photobiological, photoelectrochemical and solar thermochemical. Photobiological processes use the natural photosynthetic activity of bacteria and green algae to produce hydrogen. Photoelectrochemical processes use specialized semiconductors to separate water into hydrogen and oxygen. Solar thermochemical hydrogen production uses concentrated solar power to drive water splitting reactions often along with other species such as metal oxides.
- Biological processes
Biological processes involve the use of microbes such as bacteria and microalgae to produce hydrogen through biological reactions. In microbial biomass conversion, the microbes break down organic matter like biomass or wastewater to produce hydrogen, while in photobiological processes the microbes use sunlight as the energy source.
2. How is it used as a fuel?
Hydrogen is a clean fuel that, when consumed in a fuel cell, produces water, electricity, and heat. Hydrogen and fuel cells have the potential to play a significant role in meeting energy demands, with applications in nearly every sector — transportation, commercial, industrial, residential, and portable. Applications for hydrogen and fuel cells include distributed or combined heat and power; backup power; systems for storing and enabling renewable energy; portable power; auxiliary power for trucks, aircraft, rail, and ships; specialty vehicles such as forklifts; and passenger and freight vehicles such as cars, trucks, and buses.
3. Environmental impact
Hydrogen fuel is considered environment-friendly because it does not generate the same amount of harmful by-product as fossil fuels. However, hydrogen must be extracted from water, biomass (plant and animal waste), coal, or natural gas before it can be used. About 95% of hydrogen utilised today is obtained from steam reforming hydrogen atoms from carbon atoms in methane. The carbon dioxide released in the process could erode the ozone layer of Earth’s atmosphere and exacerbate global warming.
Which is the better gas: Methane or Hydrogen?
Methane’s warming potential is over 80 times higher than carbon dioxide in a 20-year period. The amount of methane in the atmosphere has doubled. Rising climate change concerns call for the need of switching to alternative sources of energy. Hydrogen is a potential alternative to fossil fuels due to its ability to power fuel cells in zero-emission vehicles, its potential for domestic production, and the fuel cell’s fast filling time and high efficiency. In fact, a fuel cell coupled with an electric motor is two to three times more efficient than an internal combustion engine running on gasoline. Internal combustion engines can be modified easily to run on hydrogen well.
Using hydrogen and fuel cells can achieve the following reductions in emissions:
- Light-duty highway vehicles: more than 50% to more than 90% reduction in emissions over today’s natural vehicles.
- Specialty vehicles: more than 35% reduction in emissions over current diesel and battery-powered lift trucks.
- Transit buses: demonstrated fuel economies of approximately 1.5 times greater than diesel internal combustion engine (ICE) buses and approximately 2 times higher than natural gas ICE buses.
- Auxiliary power units (APUs): more than 60% reduction in emissions compared to truck engine idling.
- Combined heat and power (CHP) systems: 35% to more than 50% reduction in emissions over conventional heat and power sources (with much greater reductions — more than 80% — if biogas or hydrogen from low- or zero-carbon sources is used in the fuel cell)
Hydrogen is being adopted worldwide as fuel to counter climate change. Here’s how Germany is striving to achieve climate neutrality by switching to hydrogen.
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References:
https://www.popularmechanics.com/science/environment/a28858699/what-is-methane/
https://www.iea-amf.org/content/fuel_information/methane
https://www.conserve-energy-future.com/sources-uses-effects-methane-gas.php
https://www.energy.gov/eere/fuelcells/hydrogen-fuel-basics
https://news.usc.edu/trojan-family/why-hydrogen-fuel-isnt-mainstream-as-fossil-fuel-alternative/
https://science.howstuffworks.com/environmental/green-science/pros-and-cons-of-hydrogen-energy.htm
https://rbac.com/methane-vs-hydrogen-vs-ch4-h2-mixes/
https://www.energy.gov/eere/articles/hydrogen-clean-flexible-energy-carrier
